Simplified prediction of deflections
In earlier chapters, we discussed how to obtain the axial strain eo and curvature y at sections of reinforced concrete frames in uncracked and cracked conditions (states 1 and 2). Ignoring concrete in tension in state 2 underestimates the rigidity of the sections. To account for the stiffening effect of concrete in the tension zone, mean values of axial strain and curvature are calculated by empirical interpolation between values of eO and y in states 1 and 2. The mean values can be employed to calculate displacements at any section by conventional methods, which generally require knowledge of the variation of the mean values over the entire length of all members (see Section 3.8 or Appendix C).